Mercurial > hg > truffle
diff src/share/vm/oops/symbol.hpp @ 11033:d9eed26d638a
8009575: Reduce Symbol::_refcount from 4 bytes to 2 bytes
Summary: Added Atomic::inc(short*) to support this change.
Reviewed-by: coleenp, dcubed, dholmes, minqi
author | iklam |
---|---|
date | Sun, 23 Jun 2013 22:08:28 -0700 |
parents | 63e54c37ac64 |
children | 9758d9f36299 |
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--- a/src/share/vm/oops/symbol.hpp Fri Jun 21 10:55:26 2013 -0700 +++ b/src/share/vm/oops/symbol.hpp Sun Jun 23 22:08:28 2013 -0700 @@ -27,6 +27,7 @@ #include "utilities/utf8.hpp" #include "memory/allocation.hpp" +#include "runtime/atomic.hpp" // A Symbol is a canonicalized string. // All Symbols reside in global SymbolTable and are reference counted. @@ -101,14 +102,22 @@ // type without virtual functions. class ClassLoaderData; -class Symbol : public MetaspaceObj { +// We separate the fields in SymbolBase from Symbol::_body so that +// Symbol::size(int) can correctly calculate the space needed. +class SymbolBase : public MetaspaceObj { + public: + ATOMIC_SHORT_PAIR( + volatile short _refcount, // needs atomic operation + unsigned short _length // number of UTF8 characters in the symbol (does not need atomic op) + ); + int _identity_hash; +}; + +class Symbol : private SymbolBase { friend class VMStructs; friend class SymbolTable; friend class MoveSymbols; private: - volatile int _refcount; - int _identity_hash; - unsigned short _length; // number of UTF8 characters in the symbol jbyte _body[1]; enum { @@ -117,7 +126,7 @@ }; static int size(int length) { - size_t sz = heap_word_size(sizeof(Symbol) + (length > 0 ? length - 1 : 0)); + size_t sz = heap_word_size(sizeof(SymbolBase) + (length > 0 ? length : 0)); return align_object_size(sz); }